Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
You have stumbled across an issue with plant equipment where the equipment passes information back to the plant so that the plant knows the available capacity of the equipment. For example, the EIR chiller passes the rated information to the plant and the plant then uses that information to choose the equipment load to be met. Here is the offending code:
MinCap = ElectricEIRChiller( EIRChillNum ).RefCap * ElectricEIRChiller( EIRChillNum ).MinPartLoadRat;
MaxCap = ElectricEIRChiller( EIRChillNum ).RefCap * ElectricEIRChiller( EIRChillNum ).MaxPartLoadRat;
OptCap = ElectricEIRChiller( EIRChillNum ).RefCap * ElectricEIRChiller( EIRChillNum ).OptPartLoadRat;
Notice that this information does not include the CapFT information, just the rated (or reference) capacity multiplied by the min/max/opt PLR. The plant then says, "hey, this equipment can only give me MaxCap, so I will request MaxCap from this equipment". To speed things up, this information is only passed to the plant once during the simulation, hence, there was no need to evaluate the CapFT curve. What you have proven is that this logic is incorrect at conditions where CapFT > 1, but at least you know why now.
